May 28, 2012 – ARGENTINA – A magnitude 6.7 earthquake struck northern Argentina early on Monday, the U.S. Geological Survey said. The quake occurred at 2:07 a.m. local time (5.07 a.m. British time) and was centered 72 miles (116 km) east-southeast of Santiago del Estero, the USGS said. There were no immediate reports of injuries or damage from the quake, which was upgraded from an initial 6.4. –Malaysian Star

Here’s a partial answer to your question:
6.0-6.9
1990 – 109
1991 – 96
1992 – 166
1993 – 137
1994 – 146
1995 – 183
1996 – 149
1997 – 120
1998 – 117
1999 – 116
So far this year (almost half over): 55
There is also data on larger magnitude earthquakes available.
So yes, there is may be a trend upward in the numbers, but compared to the past 20 years it seems to me we are about average right now. The info for 2000-2012 is located at :http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php and you can judge for yourself. Remember that we really do have better monitoring of what the earth is doing and earthquakes like this 6.7 today may not have been picked up in the past because it was so deep and in a not very populated area, as I understand it.

I was thinking the same thing! Is it possible that these quakes and the shifting crust is emitting sulpher, or other poisonous gasses? Also do you think the underwater volcano’s have any impact on this?

They reflect only a minute fraction of major quakes and most occur in the South Pacific though some occassionaly hit subduction regions like the west coast of South America. They’re called deep focus earthquakes and they generate tremendous amounts of thermal energy.